More Mosquitoes Test Positive For West Nile Virus In Sonoma County

Release date: 
Sep 3
Cotati, CA-The Marin/Sonoma Mosquito & Vector Control District announced today that additional West Nile virus (WNV) activity in Sonoma County has been detected. Another sample of mosquitoes trapped near Millbrae Avenue and Langner Avenue in Santa Rosa tested positive for WNV. This is the third time this year adult mosquitoes trapped in that area have tested positive for the virus. The last positive mosquito samples were detected on August 12th.
Adult mosquito control operations are scheduled to take place tomorrow, September 4th between the hours of 5 a.m. and 8 a.m., weather permitting. Larval control will also be conducted in areas where immature mosquitoes are found. District officials have initiated additional surveillance and trapping in the area to assess the mosquito populations and virus activity. 
"Protecting public health is our number one concern," stated Nizza Sequeira, Public Relations Director for the Marin/Sonoma Mosquito & Vector Control District. "By utilizing adult mosquito control methods we can reduce the adult mosquito populations and break the transmission cycle. This will minimize the potential for virus transmission to humans, horses and wildlife," stated Sequeira. 
Residents are urged to report mosquito problems in their areas and to reduce mosquito production sites in their yards by removing standing water on a regular basis.  Most importantly, residents should use personal protection measures against mosquito bites. Wearing long sleeved shirts, long pants and applying an effective repellent to exposed skin will help reduce the risk of WNV transmission from an infected mosquito.


2014 West Nile virus activity:


Marin County: 3 dead birds and 3 mosquito samples have tested positive for West Nile virus to date.


Sonoma County: 15 dead birds, 5 mosquito samples, 1 equine case, and 1 sentinel chicken have tested positive for West Nile virus to date.

Simple ways to help reduce exposure to mosquitoes and lessen the risk of WNV:

  • Eliminate standing water in rain barrels, old tires, buckets, kiddie pools or any other item that can hold water for more than 72-96 hours. 
  • Check septic tank lids to ensure a tight seal and repair any visible cracks.
  • Screen septic tank vent pipes using a fine mesh screen.
  • Report mosquito problems, neglected swimming pools, or any area that could be producing mosquitoes at or 1-800-231-3236.
  • Stock backyard ponds or other permanent water features with mosquitofish. The fish are free and can be delivered or simply picked up at the District office.
  • Report dead birds to the West Nile virus hotline at 1-877-968-2473 or online
  • Wear mosquito repellent when outdoors at dusk and dawn. Use a repellent containing one of the following active ingredients: DEET, Picaridin, oil of lemon eucalyptus, or IR3535. 
  • Residents interested in staying informed about district activities are encouraged to follow MSMVCD on twitter and facebook.

West Nile virus is a mosquito-borne disease that is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the disease to humans and other animals.

Less than 1% of people (about 1 in 150) infected with WNV develop serious illness. These cases may last for extended periods of time, result in permanent neurological damage and may be fatal.  

Approximately 20% of people (about 1 in 5) infected with WNV experience mild symptoms that may include fever, headache, body aches, nausea, rashes, swollen lymph nodes and vomiting. Approximately 80% of people (about 4 out of 5) infected with WNV do not show any symptoms.